ISSN:1124-318X    

DOI:10.1002/ett.4460010402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractA versatile two‐dimensional simulator for various types of semiconductor lasers for both steady state and transients has been developed. The simulator is capable of spectral analysis of quantum‐well semiconductor lasers, such as gain‐spectrum analysis, as well as analysis of the two‐dimensional current flow and optical intensity patterns. The simulator is based on the drift‐diffusion model with full Fermi‐Dirac statistics for the transport equations as well as for the Poisson equation. Simulation of the thermionic emission current is required at the abrupt heterointerfaces of the quantum well. For the spectral analysis of quantum‐well lasers, we have used the photon rate equation for each Fabry‐Perot mode. For the optical intensity pattern, we have solved the two‐dimensional Helmholtz eigenvalue equation using the subspace iteration method. The transient simulation is done by the full backward‐Euler method in conjunction with the full Newton approach for the entire semiconductor equations. To demonstrate the simulator, a model GaAs‐AIGaAs graded‐index‐separate‐confinement‐heterostructure buried

ISSN:1124-318X    

DOI:10.1002/ett.4460010403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractA physical model of a gallium arsenide MESFET, based on an improved quasi‐two‐dimensional description of the transport in the device is presented. The formulation of the model includes a comprehensive treatment of the doping profile and allows sharp variations in the profile to be reflected in the device characteristics, unlike previously published models. The model is applied to the dc and microwave characterisation of MESFETs and microwave power amplifiers. Comparison with a wide range of measured data has permitted the validation of the models for a variety of small‐signal and power de

ISSN:1124-318X    

DOI:10.1002/ett.4460010404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractSurface effects in planar submicron GaAs MESFET are investigated in detail by use of a quasi twodimensional model taking into account the nonstationary transport effects in the channel which are very important for simulation of submicron structures. The model explains the transconductance compression in submicron MESFET due to the influence of the free surface in the parasitic gate‐source and gate‐drain region. The dependence of device performance on the surface potential is sh

ISSN:1124-318X    

DOI:10.1002/ett.4460010405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThis paper describes a model for surface states on GaAs MESFETs which is used to characterise the dynamic behaviour of these traps under pulsed operating conditions. The surface charge due to trap filling is shown to be highly non‐uniform between the gate and the drain, and the form of the surface charge distribution is found to depend on the current‐voltage characteristics of the gate Schottky contact. The trap filling is calculated in a self‐consistent manner within the framework of a two‐dimensional unipolar physical simulation. The resulting model is used to investigate some anomalous features of the behaviour of the MESFET. In particular, time dependence of the gate‐drain breakdown voltage under transient conditions is explained in terms of a reduction on the gate edge electric fields as surface states near the drain end of the gate fill with excess electrons and thus become more negatively charged at high values of the drain‐gate voltage. This excess surface charge modifies the electric fields near the drain end of the gate. These calculations are supported by experimental measurements on a

ISSN:1124-318X    

DOI:10.1002/ett.4460010406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractA transient two‐dimensional hydrodynamic device simulator is presented that allows an accurate modelling of charge transport in unipolar devices made of multiple valley semiconductor material. Carrier energy balance is included to account fon non‐equilibrium transport with emphasis on heat transport by convection, which is normally not considered by GaAs device simulators. The transport model allows investigation of realistic GaAs MESFET's fabricated by ion‐implantation with gate lengths down to 0.2 μm and high channel doping.The causes of various short channel effects, namely threshold voltage variation and trans‐conductance compression are examined. It is shown that poor pinch‐off behaviour of devices with short gates has its origins much more in drain induced barrier lowering than in substrate conduction. As drain current increases with shorter gate length it could be expected that trans‐conductance would also be higher because of the larger amount of current that can be controlled by the gate. Instead, lower transconductance at zero gate bias is observed experimentally. It is known that this phenomenon can be attributed to surface depletion effects. TO test this hypothesis, a simple model for a uniform surface charge density has been included in the sirnulator. First results are in good agreement to measured dc‐parameters. Simulation also indicates that the channel narrowing due to surface depletion leads to travelling domain oscillations that are visible in the ter

ISSN:1124-318X    

DOI:10.1002/ett.4460010407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe paper proposes an extended majority‐carrier dc and ac two‐dimensional physical model for the simulation of ion‐implanted MESFETs on semi‐insulating andp‐type substrates, including the static and dynamic treatment of partly ionized impurity levels. The numerical implementation of the model is discussed, and it is shown how numerical ill‐conditioning problems suggest the implementation of a full two‐carrier model for the simulation of devices with un‐depletedp‐type substrates. A discussion is presented on the interpretation of rate‐dependent anomalies related to the frequency behaviour of the small‐signal parameters, and the importance of simulating a backgate electrode is stressed. Finally, comparisons are given with ac and dc data measured onp‐burie

ISSN:1124-318X    

DOI:10.1002/ett.4460010408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractA study of the variations of the small signal parameters of subhalf‐micron‐gate Het‐erostructure Field Effect Transistors HFETs with device scaling (aspect ratio), gate offset in the recessed zone and hot‐carrier confinement by buffer barriers is carried out for the sake of optimizing sumicron HFET structures for 40–100 GHz applications. We discuss the performance limits of existing structures and investigate new concepts and approaches to circumvent these limitations based on thorough understanding of device physics gained from 2D energy modeling. We project a net improvement in HFET millimetric performance using subhalf‐micron‐gate pseudomorphic structures which we expect to have maximum oscillation frequencies in excess of 400 GHz in th

ISSN:1124-318X    

DOI:10.1002/ett.4460010409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractA study of pseudomorphic layers properties using a selfconsistent approach is presented. The strain effects are taken into account. Sheet carrier density and capacitance voltage characteristics are related to technological layer parameters. Simple expressions of subband energy well suited for CAD are then deduced.

ISSN:1124-318X    

DOI:10.1002/ett.4460010410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe two‐dimensional device simulator PRISM (PRogram for Investigating Semiconductor Models) [1], which is a general purpose device simulator, has been adapted to simulate III‐V heterojunction FET's [2]. PRISM can now simulate silicon devices (as MOSFET's, bipolar transistors, SO1 structures, etc.,), GaAs MESFET's, Schottky diodes and AIGaAsl GaAs HEMT's.The program makes use of the finite element method to solve the Poisson equation and the finite boxes method to solve the continuity equations for electrons and holes. There is also an ongoing effort to implement the heat transport equation [3]. The finite element method has rarely been used in HEMT‐simulations. The main advantages of this method are the flexibility in defining sloped device contours and the possibilic to refine the mesh only locally, so that the number of nodes only increases moderately, as opposed to the situation with finite difference simulators. This advantage is very usefull for HEMT's were the thin AlGaAs/GaAs heterojunction region ( 40 nm) has to be simulated accurately compared to the bulk region.Simulations of AlGaAslGaAs HEMT's have been performed, and comparisons with measurements on HEMT's [4] processed in IMEC have been made. The simulated I‐V characteristics and the transconductance curves agree very well. Also sheet concentrations and band diagrams can be extracted from the simulation

ISSN:1124-318X    

DOI:10.1002/ett.4460010411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY